. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 78 M. L. PARDUE ET AL show increased activity in response to heat shock. In other cases, the hsps may be encoded by closely related genes, some activated by heat shock and some regulated in other ways. After hsps had been identified in Drosophila, it be- came evident th.^ 11 organisms make very similar sets of stress protein--. Animals, plants, and bacteria all show this heat shock , csponse, so presumably the response has been around almost as long as cells have. The conserva- tion of the major hsps is striking. For example
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 78 M. L. PARDUE ET AL show increased activity in response to heat shock. In other cases, the hsps may be encoded by closely related genes, some activated by heat shock and some regulated in other ways. After hsps had been identified in Drosophila, it be- came evident th.^ 11 organisms make very similar sets of stress protein--. Animals, plants, and bacteria all show this heat shock , csponse, so presumably the response has been around almost as long as cells have. The conserva- tion of the major hsps is striking. For example, the hsp70 of Drosophila has 48% amino acid identity with the equivalent lisp of E. coli (Bardwell and Craig. 1984). Al- though the major proteins produced in the heat shock response are strongly conserved, the stimuli that induce the response vary from organism to organism and reflect the conditions under which the organism lives. For in- stance, the temperatures that induce heat shock in Dro- sophila cells are well below those that heat shock mam- malian cells. This is not surprising because Drosophila cells usually live 10-20 degrees below the temperature of mammalian cells. Evolutionary conservation argues that the heat shock response is very important, yet we know only a little about how it helps the organism. Clearly the response helps cells endure, for a short time, temperatures slightly above what they normally tolerate. If cells are subjected to a mild heat shock and make a low level of heat shock proteins and RNA, then they can survive temperatures that would kill them if they were moved directly to those temperatures. We do not know how any of the hsps protect the cell from the heat shock, but studies of these proteins in non- stressed cells are showing that the hsps have very interest- ing roles in normal cells in addition to their roles in stressed cells. Three major families of hsps are now known to be conserved in plants, animals, and bacteria. For each of these
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
